Taxonomic Studies on 10 Species Within the Genus Impatiens Based on the Complete Chloroplast Genomes and Morphological Researches, Along With the Report of Newly Discovered Species

Southwestern China harbors high Impatiens diversity and numerous endemics, but its diversity and insufficient research have hindered clarification of their taxonomic and phylogenetic relationships. In this study, two distinct populations characterized by broadly funnelform lateral sepals were discovered in Guizhou. Given the complicated taxonomic relationships among their closely related species, further research is necessary to determine their exact taxonomic status. Investigations based on geographic proximity and morphological affinities tentatively linked the new populations to Impatiens oxyanthera , I. piufanensis , and its variety I. forrestii , as well as five other species. A taxonomic study of the aforementioned species was conducted using morphological comparison and genome sequencing (total of 10 chloroplast genomes). Phylogenetic analyses were performed based on the complete chloroplast genome sequences of 32 species across the Balsaminaceae, aiming to provide a basis for taxonomic decisions. The two new populations had 151,939 and 151,789 bp chloroplast genomes with a typical quadripartite structure, containing 113 genes. The ycf1 was identified as a potential molecular marker. Phylogenetic analysis resolved three strongly supported clades (BS = 100). These 10 chloroplast genomes exhibit high pairwise homology. The two newly discovered populations with different flower color showed 99.7% identity. Combined with morphological verification, these two populations were confirmed as conspecific, and this taxon was formally named Impatiens xishuiensis . Taxonomic revisions include recognizing I. piufanensis and I. forrestii as synonyms of I. oxyanthera , I. tienchuanensis and I. fanjingshanica as synonyms of I. commelinoides . I. sunii is probably an infraspecific entity. Although morphologically similar to I. oxyanthera , I. xishuiensis is molecularly closer to I. commelinoides . Taxonomic revisions are corroborated by both genomic and morphological data. In Impatiens , floral color is likely of relatively limited value for inferring interspecific phylogenetic affinities. This study highlights the value of chloroplast genomes in resolving phylogenetic and taxonomic complexities in Impatiens .